Window fan



FIG. 1 is a front, left, top, perspective view of a window fan showing my new design;

FIG. 2 is a front elevational view thereof, the rear being substantially a mirror image of that shown;

FIG. 3 is a left side elevational view thereof, on an enlarged scale the right side being a mirror image of that shown;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a window fan, as shown and described. 